Surface Ara

[canelaspice9]

I don’t know what I’m doing wrong. But my answer comes up to 896. What am I doing wrong?

 

[Steven G]

Well for one, the surface area is NOT 2(wxl) + (lxh) + (wxh).
The surface area is 2(wxl) + 2(lxh) + 2(wxh) or 2[(wxl) + (lxh) + (wxh)]
You double all the numbers first, then you added them. It is easier to add them first (you add smaller numbers!) and then you double (you double one number instead of three!).

Why do you think that you are doing anything wrong? All looks good to me.

 

[blamocur]

I get the same answer. And even if we assume that the boxes are "topless" my answer does not match the listed ones.

 

[canelaspice9]

Well for one, the surface area is NOT 2(wxl) + (lxh) + (wxh).
The surface area is 2(wxl) + 2(lxh) + 2(wxh) or 2[(wxl) + (lxh) + (wxh)]
You double all the numbers first, then you added them. It is easier to add them first (you add smaller numbers!) and then you double (you double one number instead of three!).

Why do you think that you are doing anything wrong? All looks good to me.

I understand that’s how you do the formula. I forgot to use the parentheses. However, my work does show that I followed the correct formula

 

[Deleted member 4993]

I understand that’s how you do the formula. I forgot to use the parentheses. However, my work does show that I followed the correct formula

Your work is very difficult to follow - l do not think any of the tutors could follow your work . Please post a clean-copy of your work.

 

[Dr.Peterson]

I don’t know what I’m doing wrong. But my answer comes up to 896. What am I doing wrong? View attachment 33949

As has been pointed out, the four choices are all wrong.

The first, 48,960, is the VOLUME of the large box.

The second, 38,880, is the VOLUME of the small box if its HEIGHT, rather than length, is 7 cm less.

The third, 10,080, is the difference of those, so it would be correct for a modified form of the problem.

The fourth, 5,440, is something I can't find.

The picture looks clearly like an open-top box. You correctly found the surface areas of both boxes including the top. (I can follow your work, but you didn't make it easy!)

The problem is HORRIBLE in several ways -- it doesn't tell you whether to count the top, doesn't tell you which dimension is which (though I think your choice is reasonable), and has very wrong choices. It even describes a "shipping box" but shows a "storage box"! And it says "small" where it means "large" ("small ... the same as the small, but ...")! I wonder if they showed the wrong picture.